Satellite Pictures: Gulf Oil Spill's Evolution

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Published May 4, 2010—Seen from space by a NASA satellite, smoke fans out (bottom center) from the BP-leased Deepwater Horizon oil rig, about 50 miles (80 kilometers) from Venice, Louisiana (map), on April 21. A day later, the oil rig would be on the floor of the Gulf of Mexico, and an ominous sheen would begin spreading toward the U.S. Gulf Coast.

When the burning rig sank on April 22, so too did the pipe connecting the rig to the 5,000-foot-deep (1,500-meter-deep) oil well. The same day a thin, iridescent, five-mile-long (eight-kilometer-long) oil slick appeared.

That day U.S. Coast Guard Rear Adm. Mary Landry told reporters that the oil sheen "probably is residual from the fire and the activity that was going on on this rig before it sank below the surface."

—With reporting by Craig Guillot in New Orleans and Marianne Lavelle

Image courtesy Jeff Schmaltz, MODIS Rapid Response Team, NASA

April 25: Oil Slick Grows, Gleams

As winds blow the oil southeast, away from land, on April 25, reflected sunlight turns the slick into an unfortunate silver lining (pictured in a NASA satellite image) for the clouds of crude now known to be gushing from the floor of the Gulf of Mexico.

At this point, the slick's "rainbow sheen" stretched about 40 by 30 miles (64 by 48 kilometers). The thick, dull layer of oil at the slick's southern edge (not visible), just above the seafloor leak site, measured roughly 16 miles (26 kilometers) long, according to a BP map.

The initial oil spill on April 22 had comprised about 8,400 gallons (31,800 liters) of oil, U.S. Coast Guard Petty Officer 3rd Class Tom Atkeson told National Geographic News on April 23, when the well was thought to have stopped leaking. That would have made it a "minor" spill, in the view of U.S. federal response agencies. (See "Oil-Spill Fears Subside at Rig-Explosion Site.")

But on April 25 the Coast Guard announced that remotely operated submersibles had found evidence that the pipe was leaking about 42,000 gallons (160,000 liters) of oil a day—a "very serious spill" and a threat to Gulf Coast ecology, Rear Adm. Mary Landry said at a press conference. (See "Oil Spill From Sunken Rig Site May Be Serious.")

Image courtesy Jeff Schmaltz, MODIS Rapid Response Team, NASA

April 26: Spill Stretches Toward Delta

Blown by welcome winds from the west-northwest, the Gulf of Mexico oil slick continued to stretch seaward on April 26. But it was also growing.

The slick's thin sheen—pictured in a European satellite radar image—was nearly a hundred miles (160 kilometers) wide at this point and about 21 miles (34 kilometers) from Louisiana's Mississippi Delta (at center-left in picture). The slick displayed thick, rusty "streamers" (picture of oil streamers) visible at closer distances, according to a BP map based on an early April 27 air survey.

That tool kit, as of April 27, included miles of tubelike booms being floated offshore to stop surface oil from spreading; remotely operated vehicles, used in an unsuccessful attempt to shut a valve on the leaking pipe; and detergent-like chemicals that break oil into smaller droplets so it can be further broken down by natural processes.

Still to come: three four-story containment "domes" to be dropped atop the seafloor leaks in mid-May and a relief well, which should stop the spill for good but will take months to drill.

Image courtesy ESA

April 29: Ill Wind Spurs Oil's Landfall

Now roughly the size of Puerto Rico, the Gulf of Mexico oil slick, propelled in part by a shift in wind direction, snakes toward the coast as seen in an April 29 NASA satellite picture.

High winds delivered a double whammy on May 1, spawning rough waters that hampered oil-cleanup efforts at sea and pushing the slick (pictured in a NASA satellite image) farther into Louisiana's wetlands.

On April 30 the joint federal-industry response team said that more than 217,000 feet (66,142 meters) of boom had been deployed to try to protect these ecologically sensitive areas and that loud cannons had been fired to "haze" birds from the water's edge.

In addition to birds, many other coastal animals were reported at risk, including heavily furred animals such as otters and nutria, or semiaquatic rodents. Dolphins and whales can get skin irritations, and sea turtles are susceptible to oil ingestion, because they often come to the surface to feed.